======================== System Clock / Date Time ======================== There might be several time giving sources like GNSS, NTP, etc that can be used to synchronize the system clock and other clock dependent parts. Synchronization --------------- Chrony is able to perform such clock synchronizations. For further information please have a look at :ref:`chronydoc`. Chrony is also able to synchronize the HW clock (RTC) automatically if it drifts away. Another tool to synchronize/handle/update the HW clock (RTC) is ``timedatectl`` which competes against chrony. **This means be cautious when synchronizing/updating the HW clock manually** HW Clock Synchronization/Update ------------------------------- As described in section above the RTC can be updated using different tools. The following sections show how this can be performed. timedatectl ~~~~~~~~~~~ **NOTE:** Using ``timedatectl`` you are able to update the HW clock manually. If no time source is present no update takes place automatically. Then a manual update is possible with: :: timedatectl set-local-rtc n Please read also the `timedatectl man page `_ when using ``timedatectl``.